Es sei u 1 , u 2 , u 3 {\displaystyle {}u_{1},u_{2},u_{3}} eine Orthonormalbasis des R 3 {\displaystyle {}\mathbb {R} ^{3}} . Zeige u 1 × u 2 = ± u 3 {\displaystyle {}u_{1}\times u_{2}=\pm u_{3}} .
